The intense intervals are based in recent research showing that even just a few minutes of training at a high intensity—really, getting as close as you can to your maximum capacity—can actually produce molecular changes within your muscles that are "comparable to those of several hours of running or bike riding."

The experts behind this workout say that it's important to have 10 seconds of rest between each exercise, and that the workout itself is super-intense and, er, "unpleasant."